Encoders are used to measure angular or linear motion. A common use of encoders is for computer numeric control (CNC) machines. In one type of encoder, e.g., a rotary encoder, an encoder disk is rotatable with a shaft of, e.g., a motor, relative to detector electronics that are mounted in a housing of the encoder. In such rotary encoders, it is generally necessary to radially align the encoder disk relative to the shaft so that the rotation axis of the shaft is coaxial to the center of the encoder disk to thereby radially align the rotation axis of the encoder disk relative to the detector electronics. It may also be necessary to gap the encoder disk relative to the detector electronics. That is, it may be necessary to axially align the encoder disk relative to the detector electronics.
Examples of gapping and centering devices are described, for example, in U.S. Pat. Nos. 5,057,684, 5,708,496, 6,714,292, European Published Patent Application No. 0 557 564, U.S. Pat. Nos. 6,452,160, 4,794,250, 4,942,295 and 4,512,184, each of which is expressly incorporated herein in its entirety by reference thereto.
In some situations, it may be desirable or a necessity to mount an encoder in a tubular or other confined space that is not significantly larger than the encoder itself. For example, servo-motors may be made using a continuous extrusion for the frame, thereby requiring the encoder to be mounted in a pocket having an inner diameter that is approximately equal to an outer diameter of motor windings. Certain of the gapping and centering devices described in U.S. Pat. Nos. 5,057,684, 5,708,496, 6,714,292, European Published Patent Application No. 0 557 564, U.S. Pat. Nos. 6,452,160, 4,794,250, 4,942,295 and 4,512,184 include a slide that is bottom mounted or centrally mounted in the encoder. Such devices may be difficult or T impossible to manipulate when installed in a close fitting pocket. Furthermore, the slides of these devices generally must extend beyond the periphery of the encoder, thereby rendering them difficult or impossible to operate when installed in, e.g., a close fitting pocket.
A conventional encoder, e.g., an encoder having a bottom mounted slide, is illustrated in FIG. 1. As illustrated in FIG. 1, a gapping slide 120 extends beyond housing 110 of the encoder when the gapping slide 120 is in the engaged position, e.g., engaging hub 104. FIG. 1 also illustrates that an encoder may include a printed circuit board (PCB) 111 and clip posts 114 that mount the PCB 111 on the housing 110.